> showing that in the English of the early 1600s, you had “an ’orse” and “an ’undred” by pronunciation, whereas all major dialects now sound the h.

I don't know what I'd call (or you're calling) 'major dialects' (just RP & GenAm?) but quite large geographic chunks of England would say "an 'orse for a 'undred", in the early 2000s.

(And 'a undred' is not a typo. I don't know why that's different, but 'an undred' just sounds wrong to me.)